Dataset Information

Loss of homeostatic tension induces apoptosis in tendon cells: an in vitro study.

ABSTRACT: Apoptosis (programmed cell death) has been identified as a histopathologic feature of tendinopathy. While the precise mechanism(s) that triggers the apoptotic cascade in tendon cells has not been identified, it has been theorized that loss of cellular homeostatic tension following microscopic damage to individual tendon fibrils could be the stimulus for initiating the pathologic events associated with tendinopathy. To determine if loss of homeostatic tension following stress deprivation could induce apoptosis in tendon cells, rat tail tendons were stress-deprived or cyclically loaded (3% strain at 0.17 Hz) for 24 hours under tissue culture conditions. Caspase-3 (an upstream mediator of apoptosis) mRNA expression was evaluated using quantitative polymerase chain reaction and caspase-3 protein synthesis was identified using immunohistochemistry. Apoptotic cells were identified histologically using an antibody for single-stranded DNA. Stress deprivation for 24 hours resulted in an increase in caspase-3 mRNA expression when compared to fresh controls or cyclically loaded tendons. Stress deprivation also increased the percentage of apoptotic cells (10.59% +/- 2.80) compared to controls (1.87% +/- 1.07) or cyclically loaded tendons (3.73% +/- 0.87). These data suggest loss of homeostatic tension following stress deprivation induces apoptosis in rat tail tendon cells.

SUBMITTER: Egerbacher M

PROVIDER: S-EPMC2505255 | biostudies-other | 2008 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:BackgroundHypercholesterolemia increases the risk of tendon pain and tendon rupture. Tendon-derived stem cells (TDSCs) play a vital role in the development of tendinopathy. Our previous research found that high cholesterol inhibits tendon-related gene expression in TDSCs. Whether high cholesterol has other biological effects on TDSCs remains unknown.MethodsTDSCs isolated from female SD rats were exposed to 10 mg/dL cholesterol for 24 h. Then, cell apoptosis was assessed using flow cytometry and fluorescence microscope. RFP-GFP-LC3 adenovirus transfection was used for measuring autophagy. Signaling transduction was measured by immunofluorescence and immunoblotting. In addition, Achilles tendons from ApoE -/- mice fed with a high-fat diet were histologically assessed using HE staining and immunohistochemistry.ResultsIn this work, we verified that 10 mg/dL cholesterol suppressed cell proliferation and migration and induced G0/G1 phase arrest. Additionally, cholesterol induced apoptosis and autophagy simultaneously in TDSCs. Apoptosis induction was related to increased expression of cleaved caspase-3 and BAX and decreased expression of Bcl-xL. The occurrence of autophagic flux and accumulation of LC3-II demonstrated the induction of autophagy by cholesterol. Compared with the effects of cholesterol treatment alone, the autophagy inhibitor 3-methyladenine (3-MA) enhanced apoptosis, while the apoptosis inhibitor Z-VAD-FMK diminished cholesterol-induced autophagy. Moreover, cholesterol triggered reactive oxygen species (ROS) generation and activated the AKT/FOXO1 pathway, while the ROS scavenger NAC blocked cholesterol-induced activation of the AKT/FOXO1 pathway. NAC and the FOXO1 inhibitor AS1842856 rescued the apoptosis and autophagy induced by cholesterol. Finally, high cholesterol elevated the expression of cleaved caspase-3, Bax, LC3-II, and FOXO1 in vivo.ConclusionThe present study indicated that high cholesterol induced apoptosis and autophagy through ROS-activated AKT/FOXO1 signaling in TDSCs, providing new insights into the mechanism of hypercholesterolemia-induced tendinopathy. High cholesterol induces apoptosis and autophagy through the ROS-activated AKT/FOXO1 pathway in tendon-derived stem cells.

Project description:BackgroundThe rate of microscopic incomplete resections of gastrointestinal cancers including pancreatic cancer has not changed considerably over the past years. Future intra-operative applications of tissue tolerable plasmas (TTP) could help to address this problem. Plasma is generated by feeding energy, like electrical discharges, to gases. The development of non-thermal atmospheric plasmas displaying spectra of temperature within or just above physiological ranges allows biological or medical applications of plasmas.MethodsWe have investigated the effects of tissue tolerable plasmas (TTP) on the human pancreatic cancer cell line Colo-357 and PaTu8988T and the murine cell line 6606PDA in vitro (Annexin-V-FITC/DAPI-Assay and propidium iodide DNA staining assay) as well as in the in vivo tumour chorio-allantoic membrane (TUM-CAM) assay using Colo-357.ResultsTTP of 20 seconds (s) induced a mild elevation of an experimental surface temperature of 23.7 degree Celsius up to 26.63+/-0.40 degree Celsius. In vitro TTP significantly (p=0.0003) decreased cell viability showing the strongest effects after 20s TTP. Also, TTP effects increased over time levelling off after 72 hours (30.1+/-4.4% of dead cells (untreated control) versus 78.0+/-9.6% (20s TTP)). However, analyzing these cells for apoptosis 10s TTP revealed the largest proportion of apoptotic cells (34.8+/-7.2%, p=0.0009 versus 12.3+/-6.6%, 20s TTP) suggesting non-apoptotic cell death in the majority of cells after 20s TTP. Using solid Colo-357 tumours in the TUM-CAM model TUNEL-staining showed TTP-induced apoptosis up to a depth of tissue penetration (DETiP) of 48.8+/-12.3μm (20s TTP, p<0.0001). This was mirrored by a significant (p<0.0001) reduction of Ki-67+ proliferating cells (80.9+/-13.2% versus 37.7+/-14.6%, p<0.0001) in the top cell layers as well as typical changes on HE specimens. The bottom cell layers were not affected by TTP.ConclusionsOur data suggest possible future intra-operative applications of TTP to reduce microscopic residual disease in pancreatic cancer resections. Further promising applications include other malignancies (central liver/lung tumours) as well as synergistic effects combining TTP with chemotherapies. Yet, adaptations of plasma sources as well as of the composition of effective components of TTP are required to optimize their synergistic apoptotic actions.

Dataset Information

Loss of homeostatic tension induces apoptosis in tendon cells: an in vitro study.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets